This work is aimed at understanding how neurons and nervous systems develop. The nervous system includes the brain, spinal cord, and sensory systems. The knowledge gained from understanding how neurons and nervous systems develop can be used to generate treatments for neurological disorders. Traditionally, work in invertebrates has motivated hypotheses for studies in the mouse mammalian system. This approach identified a number of genes that are conserved in regulating neuronal development. However, the mechanisms of neuronal patterning are not identical between systems. To compensate for these differences, the sea anemone Nematostella vectensis will be developed as a model for neuronal patterning. Nematostella represents a common ancestor of all the current model organisms and one of the oldest forms of the nervous system currently known. The relationship to current model animals will be exploited for rooting comparative studies between invertebrate and vertebrate model animals and promote identification conserved neural pathways. Additionally, Nematostella will provide a model system for studying neural regeneration mechanisms. The sea anemone undergoes extensive regeneration after injury and is amenable to forward genetic approaches. The ability to use Nematostella as comparative tool for enhancing the use of models systems and to use forward approaches to understand mechanisms regulating regeneration make this animal an excellent system for studying neurogenesis. The initial experiments in this proposal focus on characterizing the highly conserved neuronal patterning molecules of proneural and Zic during neuronal development in Nematostella. To test the role of each candidate gene we determine their expression in neurons and dividing cells using RNA in situ approaches, pattern will be determined by in situ analysis. The function of each gene will be inferred by using morpholino knockdown and mRNA injections to reduce or increase gene levels. The functional assay will be to determine the impact of these manipulations on the types of neurons that are generated. Additionally, we will label single cells expressiong each candidate during regeneration with a lineage tracing dye. From this we will be able to determine if these genes are likely involved in regulating neuronal regeneration. Finally, novel neuronal genes will be identified through a forward enhancer trap approach. This approach is achieved by mobilizing the minos transposon in a transgenic Nematostella and screening the progeny for neuronal expression. Lines with expression patterns of interest will be the focus of future studies.